Add runtime label to metrics

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

metrics/cgroups/v1/metrics.go

@@ -28,7 +28,7 @@ import (
 	v1 "github.com/containerd/containerd/metrics/types/v1"
 	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/typeurl"
-	metrics "github.com/docker/go-metrics"
+	"github.com/docker/go-metrics"
 	"github.com/gogo/protobuf/types"
 	"github.com/prometheus/client_golang/prometheus"
 )
@@ -53,7 +53,7 @@ func NewCollector(ns *metrics.Namespace) *Collector {
 	// add machine cpus and memory info
 	c := &Collector{
 		ns:    ns,
-		tasks: make(map[string]Statable),
+		tasks: make(map[string]entry),
 	}
 	c.metrics = append(c.metrics, pidMetrics...)
 	c.metrics = append(c.metrics, cpuMetrics...)
@@ -69,12 +69,19 @@ func taskID(id, namespace string) string {
 	return fmt.Sprintf("%s-%s", id, namespace)
 }
 
+type entry struct {
+	task Statable
+	// ns is an optional child namespace that contains additional to parent labels.
+	// This can be used to append task specific labels to be able to differentiate the different containerd metrics.
+	ns *metrics.Namespace
+}
+
 // Collector provides the ability to collect container stats and export
 // them in the prometheus format
 type Collector struct {
 	mu sync.RWMutex
 
-	tasks         map[string]Statable
+	tasks         map[string]entry
 	ns            *metrics.Namespace
 	metrics       []*metric
 	storedMetrics chan prometheus.Metric
@@ -109,10 +116,11 @@ storedLoop:
 	wg.Wait()
 }
 
-func (c *Collector) collect(t Statable, ch chan<- prometheus.Metric, block bool, wg *sync.WaitGroup) {
+func (c *Collector) collect(entry entry, ch chan<- prometheus.Metric, block bool, wg *sync.WaitGroup) {
 	if wg != nil {
 		defer wg.Done()
 	}
+	t := entry.task
 	ctx := namespaces.WithNamespace(context.Background(), t.Namespace())
 	stats, err := t.Stats(ctx)
 	if err != nil {
@@ -129,13 +137,17 @@ func (c *Collector) collect(t Statable, ch chan<- prometheus.Metric, block bool,
 		log.L.WithError(err).Errorf("invalid metric type for %s", t.ID())
 		return
 	}
+	ns := entry.ns
+	if ns == nil {
+		ns = c.ns
+	}
 	for _, m := range c.metrics {
-		m.collect(t.ID(), t.Namespace(), s, c.ns, ch, block)
+		m.collect(t.ID(), t.Namespace(), s, ns, ch, block)
 	}
 }
 
 // Add adds the provided cgroup and id so that metrics are collected and exported
-func (c *Collector) Add(t Statable) error {
+func (c *Collector) Add(t Statable, labels map[string]string) error {
 	if c.ns == nil {
 		return nil
 	}
@@ -145,7 +157,11 @@ func (c *Collector) Add(t Statable) error {
 	if _, ok := c.tasks[id]; ok {
 		return nil // requests to collect metrics should be idempotent
 	}
-	c.tasks[id] = t
+	entry := entry{task: t}
+	if labels != nil {
+		entry.ns = c.ns.WithConstLabels(labels)
+	}
+	c.tasks[id] = entry
 	return nil
 }
 
@@ -165,6 +181,6 @@ func (c *Collector) RemoveAll() {
 		return
 	}
 	c.mu.Lock()
-	c.tasks = make(map[string]Statable)
+	c.tasks = make(map[string]entry)
 	c.mu.Unlock()
 }